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Abstract:

According to one embodiment, a pattern forming method is disclosed. A
resist pattern having a top surface is formed pattern on a substrate. A
coating film having a first thickness distribution is formed on the
substrate. The coating film covers the resist pattern. The coating film
is thinned to expose the top surface of the resist pattern. The first
thickness distribution is changed into a second thickness distribution
which is more uniform than the first thickness distribution. The resist
pattern is removed without removing the coating film. A pattern is formed
in the substrate by processing the substrate by using the coating film as
a mask.

Claims:

1. A pattern forming method comprising: forming a resist pattern on a
substrate, the resist pattern having a top surface; forming a coating
film on the substrate, the coating film being configured to cover the
resist pattern, and the coating film having a first thickness
distribution; thinning the coating film to expose the top surface of the
resist pattern, while the first thickness distribution being changed into
a second thickness distribution by the thinning wherein the second
thickness distribution is more uniform than the first thickness
distribution; removing the resist pattern without removing the coating
film; and forming a pattern in the substrate by processing the substrate
by using the coating film after the removing the resist pattern
(hereafter referred to as "coating film pattern") as a mask.

2. The pattern forming method of claim 1, wherein forming the coating
film comprises selecting the first thickness distribution of the coating
film such that a distribution of thickness decrement of the coating film
caused by thinning the coating film is compensated by the first thickness
distribution of the coating film.

3. The pattern forming method of claim 1, wherein the substrate comprises
a semiconductor substrate and a workpiece film formed on the
semiconductor substrate, and wherein the forming a resist pattern
comprises forming a device pattern including the workpiece film by
etching the workpiece film using the coating film pattern as a mask.

4. The pattern forming method of claim 3, wherein the workpiece film is a
semiconductor film.

5. The pattern forming method of claim 3, wherein the device pattern is a
gate pattern.

6. The pattern forming method of claim 1, wherein the thinning the
coating film is performed by using RIE (Reactive Ion Etching) process, or
CMP (Chemical Mechanical Polishing) process.

7. The pattern forming method of claim 1, wherein the substrate comprises
a semiconductor substrate, a first semiconductor film formed on the
semiconductor substrate, an insulating film formed on the first
semiconductor film, and a second semiconductor film formed on the
insulating film, and wherein the forming a resist pattern on a substrate
comprises forming a first pattern including the second semiconductor film
by etching the second semiconductor film by using the coating film
pattern as a mask, forming a second pattern including the insulating film
by etching the insulating film by using the first pattern as a mask, and
forming a device pattern including the first semiconductor film by
etching the first semiconductor film by using the second pattern as a
mask.

8. The pattern forming method of claim 7, wherein the first semiconductor
film is a polycrystalline silicon film.

9. The pattern forming method of claim 7, wherein the second
semiconductor film is an amorphous silicon film.

10. The pattern forming method of claim 7, wherein the second
semiconductor film comprises carbon.

11. The pattern forming method of claim 7, wherein the device pattern is
a gate pattern.

12. The pattern forming method of claim 1, wherein the forming a coating
film is performed using a spin-coating method, and wherein the spin
coating method is performed such that the coating film has the first
thickness distribution by controlling at least one of amount of coating
solution discharged from a nozzle toward the substrate, and spin speed of
the substrate.

13. The pattern forming method of claim 1, wherein the forming a coating
film is performed using an ink-jet coating method, and wherein the spin
coating method is performed such that the coating film has the first
thickness distribution by controlling at least one of number of droplets
on the substrate in which the droplets are discharged from a ink-jet head
toward the substrate, and amount of one droplet discharged from the
ink-jet head toward the substrate.

14. The pattern forming method of claim 1, wherein the forming a coating
film is performed using a scan coating method, and wherein the scan
coating method is performed such that the coating film has the first
thickness distribution by controlling at least one of amount of coating
solution discharged from a nozzle toward the substrate, and scan speed of
the nozzle.

15. The pattern forming method of claim 1, wherein the forming a coating
film is performed using a spiral coating method, and wherein the spiral
coating method is performed such that the coating film has the first
thickness distribution by controlling at least one of amount of coating
solution discharged from a nozzle toward the substrate, moving speed of
the nozzle from a center of the substrate toward outer edge of the
substrate, and spin speed of the substrate.

16. A semiconductor device manufacturing method comprising: preparing a
substrate; and forming a plurality of line and space patterns on the
substrate, the plurality of line & space patterns being equal in height
and being different in half pitch, the plurality of line & space patterns
comprising at least one line & space pattern having a half pitch not
higher than a certain value; forming a plurality of line and space
patterns on the substrate, the plurality of line & space patterns being
same in aspect rations and being different in half pitch, the plurality
of line & space patterns comprising at least one line & space pattern
having a half pitch not higher than a certain value; wherein the at least
one line & space patterns is formed by pattern forming method, the
pattern forming method comprising: forming a resist pattern on a
substrate, the resist pattern having a top surface; forming a coating
film on the substrate, the coating film being configured to cover the
resist pattern, and the coating film having a first thickness
distribution; thinning the coating film to expose the top surface of the
resist pattern wherein the first thickness distribution is changed into a
second thickness distribution which is more uniform than the first
thickness distribution; removing the resist pattern without removing the
coating film; and forming the at least one line & space pattern in the
substrate by processing the substrate by using the coating film after the
removing the resist pattern as a mask.

17. The semiconductor device manufacturing method of claim 16, wherein
the certain value is not higher than 20 nm.

18. The semiconductor device manufacturing method of claim 16, wherein
the aspect ratio is not higher than 2.5.

19. A coating apparatus comprising: a holding unit configured to hold a
substrate on which a coating film is to be formed; a rotating unit
configured to rotate the substrate held by the holding unit; a
discharging unit comprising a nozzle from which coating solution is
discharged toward the substrate held by the holding unit; a moving unit
configured to move the nozzle in a radial direction of the substrate held
by the holding unit; and a controlling unit configured to control at
least one of spin speed of the substrate rotated by the rotating unit,
amount of coating solution discharged from the nozzle of the discharging
unit, and moving speed of the nozzle moved by the moving unit, to form a
coating film having a desired thickness distribution on the substrate.

20. The coating apparatus of claim 19, wherein when the coating film is
being formed, the substrate held by the holding unit is rotated by the
rotating unit, and the nozzle is moved in the radial direction of the
substrate by the moving unit.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priority
from Japanese Patent Application No. 2012-036375, filed Feb. 22, 2012,
the entire contents of which are incorporated herein by reference.

FIELD

[0002] Embodiments described herein relate generally to a pattern forming
method used for manufacturing a semiconductor device, a semiconductor
device manufacturing method, and a coating apparatus.

BACKGROUND

[0003] A semiconductor device manufacturing method generally includes the
step of forming a resist pattern on a workpiece substrate including a
semiconductor substrate and the step of etching the workpiece substrate
by using the resist pattern as a mask to form a micropattern. The step of
forming the resist pattern and the step of etching the workpiece
substrate are repeated to form a necessary pattern, thereby manufacturing
a semiconductor device.

[0004] However, the progress of pattern miniaturization causes a
difficulty in forming a fine pattern having both desired shape and
dimensions even if etching the workpiece substrate by using the resist
pattern as a mask.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a sectional view to explain a pattern forming method
according to a first embodiment;

[0006] FIG. 2 is a sectional view to explain the pattern forming method of
the first embodiment following FIG. 1;

[0007] FIG. 3 is a sectional view to explain the pattern forming method of
the first embodiment following FIG. 2;

[0008] FIG. 4 is a sectional view to explain the pattern forming method of
the first embodiment following FIG. 3;

[0009] FIG. 5 is a sectional view to explain the pattern forming method of
the first embodiment following FIG. 4;

[0010] FIG. 6 shows a distribution of etching rates of a coating film in a
plane of substrate;

[0011] FIG. 7 shows a distribution of variations in the etching rate of
the coating film in a plane of substrate obtained by changing etching
conditions;

[0012] FIG. 8 is a diagram to explain an aspect of a line & space pattern;

[0013] FIGS. 9A, 9B, and 9C are diagrams to explain an example of forming
a coating film by spin coating method;

[0014] FIGS. 10A and 10B are diagrams to explain an example of forming a
coating film by ink-jet coating method;

[0015] FIGS. 11A and 11B are diagrams to explain an example of forming a
coating film by scan coating method;

[0016] FIGS. 12A and 12B are diagrams to explain an example of forming a
coating film by spiral coating method;

[0017] FIG. 13 is a sectional view to explain a pattern forming method
according to a second embodiment;

[0018] FIG. 14 is a sectional view to explain the pattern forming method
of the second embodiment following FIG. 13;

[0019] FIG. 15 is a sectional view to explain the pattern forming method
of the second embodiment following FIG. 14;

[0020] FIG. 16 is a sectional view to explain the pattern forming method
of the second embodiment following FIG. 15;

[0021] FIG. 17 is a sectional view to explain the pattern forming method
of the second embodiment following FIG. 16;

[0022] FIG. 18 is a sectional view to explain the pattern forming method
of the second embodiment following FIG. 17;

[0023] FIG. 19 is a sectional view to explain the pattern forming method
of the second embodiment following FIG. 18; and

[0024] FIG. 20 is a diagram schematically showing a coating apparatus
according to an embodiment.

DETAILED DESCRIPTION

[0025] Hereinafter, embodiments will be explained with reference to the
accompanying drawings.

[0026] In general, according to one embodiment, a pattern forming method
is disclosed. The pattern forming method includes forming a resist
pattern on a substrate. The resist pattern has a top surface. A coating
film is formed on the substrate. The coating film is configured to cover
the resist pattern. The coating film has a first thickness distribution.
The coating film is thinned to expose the top surface of the resist
pattern. The first thickness distribution is changed into a second
thickness distribution when the coating film is thinned. Here, the second
thickness distribution is more uniform than the first thickness
distribution. The resist pattern is removed without removing the coating
film. A pattern is formed in the substrate by processing the substrate by
using the coating film after the removing the resist pattern as a mask.

[0027] According to one embodiment, a semiconductor device manufacturing
method is disclosed. The semiconductor device manufacturing method
includes preparing a substrate, and forming a plurality of line and space
patterns on the substrate. The plurality of line & space patterns are
equal in heighty and being different in half pitch. The plurality of line
& space patterns includes at least one line & space pattern having a half
pitch not higher than a certain value. The at least one line & space
pattern is formed by a pattern forming method according to the
embodiment.

[0028] According to one embodiment, a coating apparatus is disclosed. The
coating apparatus includes a holding unit configured to hold a substrate
on which a coating film is to be formed, a rotating unit configured to
rotate the substrate held by the holding unit, a discharging unit
comprising a nozzle from which coating solution is discharged toward the
substrate held by the holding unit, a moving unit configured to move the
nozzle in a radial direction of the substrate held by the holding unit.
The coating apparatus further includes a controlling unit configured to
control at least one of spin speed of the substrate rotated by the
rotating unit, amount of coating solution discharged from the nozzle of
the discharging unit, and moving speed of the nozzle moved by the moving
unit, to form a coating film having a desired thickness distribution on
the substrate.

First Embodiment

[0029] FIGS. 1 to 5 are sectional views to explain a pattern forming
method according to a first embodiment.

[0030] [FIG. 1]

[0031] First, a workpiece film 2 is formed on a silicon substrate 1. In
the present embodiment, the silicon substrate 1 and workpiece film 2 are
collectively called a substrate. The workpiece film 2 is, for example, an
insulating film such as a silicon oxide film, or a semiconductor film
such as a polycrystalline silicon film. Next, a resist pattern 3 is
formed on the workpiece film 2. The resist pattern 3 is formed by, for
example, optical lithographic process or an imprint lithographic process.

[0032] [FIG. 2]

[0033] A coating film 4 having a certain thickness distribution and
covering the resist pattern 3 is formed on the substrate by coating
method. The certain thickness distribution is not uniform. The certain
thickness distribution will be explained later.

[0034] [FIG. 3]

[0035] The top surface of the resist pattern 3 is exposed by thinning the
coating film 4 by etch back. The etch back is performed by using, for
example, Reactive Ion Etching (RIE) process. In the present embodiment,
side surfaces of the upper portions of the resist pattern 3 are also
exposed. In place of the RIE process, Chemical Mechanical Polishing (CMP)
process may be used.

[0036] Here, the certain thickness distribution is selected so as to
cancel a distribution of thickness decrement of the coating film caused
by the thinning the coating film by etch back.

[0037] The reason for decreasing of the thickness due to the etch back is
that the etching rate (E/R) of the coating film 4 in the surface of the
substrate varies with position (X) as shown in FIG. 6. X is a horizontal
axis passing through the center of in-plane surface of the substrate.
FIG. 6 shows an example in the horizontal direction, but a similar
distribution to that of FIG. 6 is obtained with respect to the axis
passing through the center of in-plane surface of the substrate. This is
because the etching rate principally varies from the center of in-plane
surface of the substrate toward the outer edge.

[0038] Such an etching rate variation of the coating film over in-plane
surface of the substrate may change depending on etching conditions. In
the case of RIE, the etching rate may change with, for example, gas
mixing ratio, gas flow rate, or applied voltage.

[0039] FIG. 7 shows a distribution of variations in the etching rate of
the coating film in the plane of substrate obtained by changing etching
conditions. The etching rate was calculated based on etching time, and
the difference between the thickness of the coating film before etching
and thickness of the coating film after etching. The thickness of the
coating film after etching can be obtained using, for example, an
ellipsometer.

[0040] As seen from FIG. 7, there are the following distributions: a
distribution (the top distribution) where the etching rate decreases from
the middle (X=0) toward the outer edge, a distribution (the second
distribution from the top) where the etching rate decreases from the
middle (X=0) halfway toward the outer edge, then increases, and decreases
again toward the outer edge, distributions (the third and fourth
distributions from the top) where the etching rate decreases from the
middle (X=0) halfway toward the outer edge, then increases, and reaches
the peak at the outer edge, and a distribution (the bottom distribution)
where the etching rate increases from the middle (X=0) toward the outer
edge.

[0041] In the present embodiment, the thickness distribution of the
coating film 4 in the step of FIG. 2 is determined, taking into account
of the distribution of thickness decrement of the coating film due to the
etch back. That is, the coating film 4 is made thicker in a portion where
the amount of thickness decrement to the etch back is larger, whereas the
coating film 4 is made thinner in a portion where the amount of thickness
decrement due to the etch back is smaller (FIG. 2), thereby the thickness
of the coating film 4 after the etch back is made as uniform as possible
over the in-plane of the substrate (FIG. 3).

[0042] [FIG. 4]

[0043] The resist pattern 3 is selectively removed with respect to the
coating film 4. The resist pattern 3 is removed by, for example,
carbonization process. The coating film (coating film pattern) 4 remained
after the removal of the resist pattern 3 has a reversal pattern of the
resist pattern 3. The coating film pattern 4 has a uniform thickness over
the in-plane surface of the substrate.

[0044] [FIG. 5]

[0045] A pattern comprising the workpiece film 2 is formed by etching the
workpiece film 2 by using the coating film pattern 4 as a mask. When the
workpiece film 2 is a semiconductor film such as a polycrystalline
silicon film, for example, a gate pattern (gate electrode) is formed.
When the workpiece film 2 is an insulating film, for example, a contact
hole pattern is formed. The conventional method has a difficulty in
forming a fine pattern having a half pitch of 20 nm or less, but the
method of the present embodiment may easily form the fine pattern having
the half pitch of 20 nm or less,

[0046] The reason for employing the process (reversal process), where the
workpiece film 2 is etched by using the resist pattern 3 instead of
resist pattern 3 as a mask, is as follows.

[0047] In the present process, as shown in FIG. 8, the aspect ratio (=B/A)
of the resist pattern 3 for a line & space pattern is low. Its value is,
for example, 2.5. Here, A indicates the width of the resist pattern 3,
and B indicates the thickness (height) of the resist pattern 3.

[0048] The width A narrows as the shrinkage of pattern advances. Since the
aspect ratio is fixed, the thickness B decreases in accordance with
decreasing of the width A. Therefore, as the miniaturization progresses,
the resist pattern 3 becomes thinner. When the workpiece film 2 is etched
by using the thin resist pattern 3, the resist pattern 3 disappears
during the etching, and then the workpiece film 2 may not be processed
into a pattern having predetermined shape and dimensions. Such a problem
becomes more significant when it is difficult to ensure the etching
selectivity between the resist pattern 3 and the workpiece film 2.

[0049] In contrast, when the workpiece film 2 is etched by using the
coating film pattern 4 as a mask, the etching rate of coating film
pattern 4 to the workpiece film 2 can be generally set lower compared to
the resist by appropriately selecting the material of the coating film
pattern 4.

[0050] However, in a case where the resist pattern 3 has a variation in
the thickness, the thin portion of the resist pattern disappears during
etching of the workpiece film 2, which may result in a similar problem as
the case of using the resist pattern. In addition, the variation of the
thickness of the coating film pattern 4 may cause difficulty in forming
the pattern having the shape and dimensions in accordance with design
even if a part of the coating film pattern 4 does not disappear.

[0051] Therefore, in the present embodiment, the problem due to the
variation of thickness of the coating film pattern 4 is forestalled by
forming the coating film 4 in the step of FIG. 2 where the coating film 4
has the thickness distribution that cancels the distribution of thickness
decrement of the coating film which arises in the etch back step of FIG.
3. Thereby, according to the present embodiment, the advantage of
reversal process is obtained, which result in providing a pattern forming
method capable of dealing with further pattern miniaturization in the
future.

[0052] Next, a method of forming the coating film having a certain
thickness distribution will be explained.

[0053] First, the distribution of thickness decrement of the coating film
(thickness loss distribution) is prepared where the thickness loss
distribution is caused by thinning the coating film pattern by etching
back. Since the thickness loss distribution may differ depending on
etching conditions (e.g., conditions of RIE), the thickness loss
distribution is prepared for each of the etch back conditions used for
reversal process.

[0054] Next, the step of forming the coating film pattern 4 shown in FIG.
2, wherein the coating film pattern 4 shown is made to have a thickness
distribution (thickness correction distribution) capable of cancelling
the thickness loss distribution by controlling the formation condition of
coating method.

[0055] For example, when the coating film is formed by spin-coating
method, as shown in FIG. 9C, the coating film 94 having the thickness
correction distribution can be formed by controlling at least one of
amount of coating solution 92 discharged (dropped) from a nozzle 91
toward a substrate 93 (discharge rate) as shown in FIG. 9A, and spin
speed V1 [rpm] of the substrate 93 as shown in FIG. 9B, for example,
spinning the substrate 93 at the pin speed V1=2000 [rpm], causing the
coating solution to spread widely over the substrate 93.

[0056] When the coating film is formed by ink-jet coating method, as shown
in FIG. 10B, the coating film 104 having the thickness correction
distribution can be formed by controlling, as shown in FIG. 10A, at least
one of number of droplets 102 per unit area on the substrate 103 in which
the droplets 102 are discharged from a ink-jet head 101 toward the
substrate 103 and amount of one droplet 102 discharged from the ink-jet
head 101 toward the substrate 103. In general, the thickness of the
coating film on a region becomes thicker as the number of droplets per
unit area on the region increases, or as the amount of one droplet on the
region increases. The amount of droplets per unit area is controlled by
changing the number of droplets per unit area while the amount of one
droplet is constant. Conversely, the amount of droplets per unit area is
also controlled by changing the amount of one droplet while the amount of
droplets per unit area is constant.

[0057] When the coating film is formed by scan coating method, as shown in
FIG. 11B, the coating film 114 having the thickness correction
distribution can be formed on the substrate 113 by controlling, as shown
in FIG. 11A, at least one of amount of coating solution 112 discharged
from a nozzle 11 toward the substrate (discharge rate), and scan speed V2
of the nozzle 111. In general, the thickness of the coating film on a
region becomes thicker as the discharge rate on the region increases, or
as the scan speed V2 on the region decreases.

[0058] When a coating film is formed by spiral coating method, as shown in
FIG. 12B, the coating film 114 having the thickness correction
distribution can be formed by controlling, as shown in FIG. 12A, at least
one of amount of coating solution discharged from a nozzle 121 toward the
substrate (discharge rate), moving speed V3 of the nozzle 121 from a
center of the substrate 122 toward outer edge of the substrate 122, and
spin speed V4 of the substrate 122. In general, the thickness of the
coating film on a region becomes thicker as the discharge rate on the
region increases, or as the scan and moving speeds V3, V4 on the region
decreases.

Second Embodiment

[0059] FIGS. 13 to 19 are sectional views to explain a pattern forming
method according to a second embodiment. In the following figures, the
portions corresponding to the portions shown in the previously mentioned
figures are denoted by the same reference numerals and omitted its detail
explanation.

[0060] [FIG. 13]

[0061] First, a polycrystalline silicon film (a first semiconductor film)
21 is formed on a silicon substrate 1. Next, a silicon oxide film (an
insulating film) 31 is formed on the polycrystalline silicon film 21.
Then, an amorphous silicon film (a second semiconductor film) 41 is
formed on the silicon film 31. In the present embodiment, the silicon
substrate 1, polycrystalline silicon film 21, silicon oxide film 31, and
amorphous silicon film (a-Si film) 41 are collectively called a
substrate. Next, a resist pattern 3 is formed on the a-Si film 41.

[0062] [FIG. 14]

[0063] A coating film 4 having a certain thickness distribution and
covering the resist pattern 3 is formed on the substrate by coating
method.

[0064] [FIG. 15]

[0065] The coating film 4 is thinned by etch back, causing the top surface
of the resist pattern 3 to be exposed. The thickness distribution of the
coating film 4 after the etch back is almost uniform.

[0066] [FIG. 16]

[0067] The resist pattern 3 is selectively removed with respect to from
the coating film 4. The coating film (coating film pattern) 4 remained
after the removal of the resist pattern 3 has a reversal pattern of the
resist pattern 3, and the coating film pattern 4 has a uniform thickness
over the in-plane surface of the substrate.

[0068] [FIG. 17]

[0069] the coating film pattern 4 is transferred to the a-Si film 41 by
etching the a-Si film 41 by using the coating film pattern 4 as a mask.
Hereinafter, the a-Si film 41 having the pattern transferred is called an
a-Si film pattern 41.

[0070] [FIG. 18]

[0071] The a-Si film pattern 41 is transferred to the silicon oxide film
31 by etching the a-Si film pattern 41 by using the coating film pattern
4 and a-Si film pattern 41 as a mask, or by using the a-Si film pattern
41 remained after the removal of the coating film pattern 4 as a mask.
Hereinafter, the silicon oxide film 31 having transferred the silicon
oxide film pattern 31 is called a silicon oxide film pattern 31.

[0072] When the coating film pattern 4 and a-Si film 41 are used as a
mask, the coating film pattern 4 disappears in the middle of etching the
silicon oxide film 31. This is because the coating film pattern 4 and
silicon oxide film 31 are both insulating films and therefore a
sufficient etching selectivity is not ensured. After the coating film
pattern 4 has disappeared, the etching of the silicon oxide film 31
progresses by using the a-Si film 41 as a mask.

[0073] [FIG. 19]

[0074] The silicon oxide film pattern 31 is transferred to the
polycrystalline silicon film 21 by etching the polycrystalline silicon
film 21 by using the a-Si film pattern 41 and silicon oxide film pattern
31 as a mask, or by using the silicon oxide film pattern 31 remained
after the removal of the a-Si film 41 as a mask.

[0075] When the a-Si film pattern 41 and silicon oxide film pattern 31 are
used a mask, the a-Si film pattern 41 disappears in the middle of etching
the polycrystalline silicon film 21. This is because both of the a-Si
film pattern 41 and polycrystalline silicon film 21 are silicon films and
therefore the etching selectivity of them is not ensured. After the a-Si
film pattern 41 has disappeared, the etching of the polycrystalline
silicon film 21 progresses by using the silicon oxide film pattern 31 as
a mask.

[0076] Thereafter, the silicon oxide film pattern 31 is removed, then a
device pattern formed of the polycrystalline silicon film 21 is obtained.
This device pattern is, for example, a gate pattern (gate electrode).

[0077] According to the present embodiment, the advantage of reversal
process is obtained, same as the first embodiment, which result in
providing a pattern forming method capable of dealing with further
pattern miniaturization in the future.

[0078] Further, in the present embodiment, the polycrystalline silicon
film 21 is not directly etched by using the coating film pattern 4 as a
mask, in which the coating film pattern 4 is obtained by the reversal
process. According to the present embodiment, the mask is effectively
suppressed from being disappeared in the middle of etching because the
polycrystalline silicon film 21 is eventually etched by using the mask of
the silicon oxide film pattern 31 that is thicker than the coating film
pattern 4.

[0079] Furthermore, in the present embodiment, the silicon oxide film is
etched by using the mask of a-Si film pattern 41 that has a sufficient
etching selectivity to silicon oxide.

[0080] Additionally, a pattern of film including carbon (C) may be used
instead of the a-Si film pattern 41. Moreover, an insulating film pattern
including silicon nitride, or an insulating film pattern including
silicon nitride and silicon oxide may be used instead of the silicon
oxide film pattern 31.

[0081] Furthermore, the pattern forming method of the first or second
embodiment is applicable to a semiconductor device manufacturing method.
That is, in a case of manufacturing a semiconductor device comprising a
plurality of line & space patterns, which have low aspect ratios (e.g.,
2.5 or less) and the same heights, but which are different in half pitch,
the line & space patterns having the half pitch not higher than a certain
value (e.g., 20 nm) are formed by the pattern forming method of the
embodiment.

[0082] FIG. 20 schematically shows a coating apparatus according to an
embodiment for forming the coating film of the first or second embodiment
by spiral coating method.

[0083] The coating apparatus of the present embodiment comprises a stage
202 configured to place the substrate 1 thereon and having an
electrostatic chuck mechanism 201 for holding the substrate 1, and a
rotating mechanism 203 configured to rotate the substrate 1 that is hold
by the electrostatic chuck mechanism 201 and is placed on the stage 202.
The rotating mechanism 203 comprises a rotation axis fixed to the stage
202 and a motor mechanism 203b for rotating the rotation axis 203a.

[0084] The coating apparatus of the embodiment further comprises a
discharge mechanism 204 which includes a nozzle 204a for discharging
coating solution toward the substrate 1 held by the electrostatic chuck
mechanism 201 and placed on the stage 202. The discharge mechanism 204
further includes a tank 204b that accumulates coating solution, a supply
tube 204c that connects the tank 204b and the nozzle 204a to supply
coating solution in the tank 204b to the nozzle 204a, and a flow
regulating valve (not shown) of the solution.

[0085] The coating apparatus of the present embodiment further comprises a
movement mechanism 205 for moving the nozzle 204a in the radial direction
of the substrate 1 held by the electrostatic chuck mechanism 201 and
placed on the stage 202. The movement mechanism 205 includes an arm
module 205a connected to the nozzle 204a, and a drive module 205 for
moving the arm module 205a in the radial direction of the substrate 1.

[0086] The coating apparatus of the embodiment further comprises a control
mechanism 206 for controlling the rotating mechanism 203, discharge
mechanism 204, and movement mechanism 205.

[0087] Here, a the control mechanism 206 is configured to control at least
one of spin speed of the substrate 1 rotated by the rotating mechanism
203, amount of coating solution discharged from the discharge mechanism
204, and moving speed of the nozzle 204a moved by the movement mechanism
205 in accordance with the position of the nozzle 204a on the substrate 1
to form a coating film having a desired thickness distribution on the
substrate 1 by rotating the substrate 1 held by the electrostatic chuck
mechanism 201 and placed on the stage 202 while the nozzle 204a is moved
in the radial direction of the substrate 1.

[0088] In the above embodiment, the thickness distribution is selected so
as to cancel the distribution of thickness decrement of the coating film
4 caused by the thinning the coating film 4 (distribution A) when the
coating film 4 is formed on the substrate in a manner that the resist
pattern 3 is covered by the coating film 4. However, the thickness
distribution may be selected so as to further cancel the distribution of
thickness decrement of the coating film 4 caused by the removal of the
resist pattern 3 (distribution B) (canceling distributions A and B). In
this case, one of distribution A and distribution B may be cancelled
preferentially and the other may not be cancelled completely.

[0089] In addition, the thickness distribution may be selected so as to
cancel the distribution of thickness decrement of the coating film 4
caused by etching the substrate by using the coating film pattern 4 as a
mask (distribution C) in addition to cancel the distribution A (canceling
distributions A and C).

[0090] Moreover, the thickness distribution of the coating film 4 may be
selected so as to cancel distribution A, distribution B, and distribution
C. In this case, at least one of distribution A, distribution B, and
distribution C may be cancelled preferentially and the remaining ones may
not be cancelled completely.

[0091] While certain embodiments have been described, these embodiments
have been presented by way of example only, and are not intended to limit
the scope of the inventions. Indeed, the novel embodiments described
herein may be embodied in a variety of other forms; furthermore, various
omissions, substitutions and changes in the form of the embodiments
described herein may be made without departing from the spirit of the
inventions. The accompanying claims and their equivalents are intended to
cover such forms or modifications as would fall within the scope and
spirit of the inventions.